JPH10121103A - Flat iron base alloy powder for flame retardant magnetic shield - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide flat Fe base alloy powder for a magnetic shield excellent in flame retardancy and used for the formation of a magnetic shield layer, a magnetic shield sheet or the like for protecting various magnetic recording devices and electronic equipment from the bad influences of magnetic fields and electromagnetic waves. SOLUTION: This flat Fe base alloy powder for a magnetic shield is the one in which the average thickness (d) is regulated to 0.05 to 0.6μm and, in the case the weight is accumulated from the one small in the particle diameter obtd. by a particle diameter distributing gauge, the particle diameter D accumulated to 10% is defined as D10 and the particle diameter D accumulated to 50% is defined as D50 , D10 is regulated to 4.5 to 10μm, also, D50 is regulated to 10 to 40μm, and the aspect ratio (D50 /d) is regulated to 20 to 200. In this case, the componental compsn. is composed of the one contg., by atom, 15 to 30% M (where M denotes one or two kinds of Al and Si), 3 to 15% Cr, 3 to 6% O, 0.05 to 2% N, and the balance Fe with inevitable impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant magnetic shield used for forming a magnetic shield layer or a magnetic shield sheet for protecting various magnetic recording devices and electronic devices from the adverse effects of magnetic fields and electromagnetic waves. The present invention relates to a flat Fe-based alloy powder.

[0002]

2. Description of the Related Art Conventionally, as a flat Fe-based alloy powder for a magnetic shield, for example, as described in JP-A-3-295206, Si:
%, Cr: 0 to 6%, and the remainder is known to have a composition of Fe and inevitable impurities.

[0003] Further, in practical use, such as the flat Fe-based alloy powder for a magnetic shield described above, the average thickness (hereinafter referred to as d): 0.02 to 0.6 µm, which is determined by a particle size distribution analyzer. the particle size of when it is 50% from smaller particle sizes and total weight (hereinafter indicated by D _50): 3~60μm, the aspect ratio (hereinafter, indicated by D ₅₀ / d): 20~500 It is also well known that it is used after being adjusted.

[0004] When the contents of nitrogen and oxygen contained as unavoidable impurities in these conventional flat Fe-based alloy powders for magnetic shielding were measured, the oxygen content was 0.5 to 2.0.
It was also found that the atomic% and the nitrogen content were about 0.02 atomic%.

[0005]

The demand for flat Fe-based alloy powders for magnetic shielding has been increasing more and more in recent years. However, when handling large amounts of conventional flat Fe-based alloy powder for magnetic shielding, ignition may occur due to static electricity or friction. Particularly in a work environment using synthetic resins or organic solvents, accidents due to ignition may occur. For the prevention, a flame-retardant powder has been required as much as possible.

[0006]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of researching to develop a flat Fe-based alloy powder for magnetic shields having better flame retardancy than before, as a result of nitriding and oxidizing the flat Fe-based alloy powder for magnetic shield, nitrogen: 0.05 to 2 atomic%, oxygen: 3 to 6
Atomic% and d is 0.05-0.6μ
m, the particle size when the weight is accumulated to 10% from the smaller particle size obtained by the particle size distribution meter (hereinafter, D ₁₀
Is 4.5 to 10 μm, D ₅₀ is 10 to 40 μm, and D ₅₀ / d is 20 to 200, the flat Fe-based alloy powder for a magnetic shield having such a configuration has more flame retardancy than the conventional one. The research result of improvement was obtained.

The present invention has been made based on the results of such research, and has a d: 0.05 to 0.6 μm,
₁₀ : 4.5 to ₁₀ μm, D ₅₀ : 10 to 40 μm, D ₅₀ /
d: 20 to 200, and in atomic%, M (where M
Is one or two of Al or Si): 15 to 3
0%, Cr: 3 to 15%, O: 3 to 6%, N: 0.05
This is characterized by a flat Fe-based alloy powder for a flame-retardant magnetic shield having a component composition consisting of Fe and unavoidable impurities.

The flat F for a flame-retardant magnetic shield is described below.
The reason why the component composition, d, D ₁₀ , D ₅₀ , and D ₅₀ / d of the e-base alloy powder are limited as described above will be described. (A) M (Al or one or two of Si) M content coercivity is less than 15 atomic percent (hereinafter indicated by H _c) preferably the magnetic shielding performance is reduced because the higher without the other hand, when the content exceeds 30 atomic%, the powder saturation magnetization (hereinafter, indicated by sigma _s) it is not sufficient magnetic shielding performance is obtained because lowered. Therefore, M
Was determined to be 15 to 30 atomic%. A more preferable range of the content of M is 18 to 25 atomic%.

(B) Cr If the Cr content is less than 3 atomic%, rust and discoloration are liable to occur at the stage of coarse pulverization and flattening of the raw material ingot, so that it is not preferable. If the content exceeds the above range, the powder σ _s decreases, so that sufficient magnetic shielding performance cannot be obtained. Therefore, the content of Cr is 3
-15 atomic%. A more preferable range of the Cr content is 5 to 10 atomic%.

(C) O O has the effect of improving the flame retardancy of the flat Fe-based alloy powder for magnetic shielding, but if its content is less than 2 atomic%, a sufficient effect of improving the flame retardancy can be obtained. On the other hand, if the content exceeds 6 atomic%, it is not preferable because H _c increases and σ _s decreases, and the magnetic shielding performance decreases. Therefore, the content of O is set to 3 to 6 atomic%.
A more preferable range of the O content is 3.5 to 4.5 atomic%.
It is.

(D) NN also has the effect of improving the flame retardancy of the flat Fe-based alloy powder for magnetic shielding, but if its content is less than 0.05 atomic%, a sufficient effect of improving the flame retardancy cannot be obtained. Not obtained, while 2
When the content exceeds atomic%, H _c increases and σ
_s decreases, and the magnetic shielding performance decreases, which is not preferable. Therefore, the content of N is set to 0.05 to 2 atomic%. A more preferable range of the content of N is 0.1 to 1.N.
0 atomic%.

(E) If d is less than 0.05 μm, a sufficient flame-retardant effect cannot be obtained, while if d exceeds 0.6 μm, the magnetic shielding performance is undesirably deteriorated. Therefore, d
Was set to 0.05 to 0.6 μm. A more preferable range of d is 0.1 to 0.3 μm.

(F) D _{10 If} D ₁₀ is reduced to less than 4.5 μm, a sufficient effect of improving the flame retardancy cannot be obtained. On the other hand, if D ₁₀ exceeds 10 μm, it becomes difficult to increase the powder filling rate. It is not preferable because the magnetic shield performance is deteriorated. Therefore, D10 was set to 4.5 to ₁₀ μm. A more preferred range of D ₁₀ is 5～8Myuemu.

(G) D _{50 When} D ₅₀ is reduced to less than 10 μm, a sufficient effect of improving flame retardancy cannot be obtained. On the other hand, when D ₅₀ exceeds 40 μm, D ₅₀ exceeds 40 μm.
It is not preferable because a uniform magnetic shield layer cannot be obtained.
Thus, D ₅₀ was determined to be 10 to 40 [mu] m. A more preferred range of D ₅₀ is 15 to 30 [mu] m.

(H) D ₅₀ / d If D ₅₀ / d is less than 20, the magnetic resistance of the magnetic shield layer is undesirably increased, while D ₅₀ / d is not more than 20.
If it exceeds 0, a sufficient flame retardancy improving effect cannot be obtained. Thus, D ₅₀ / d was set to 20 to 200. D ₅₀ / d
Is more preferably 40 to 100.

The flat F for a flame-retardant magnetic shield of the present invention
e-base alloy powder, high-frequency melting of the alloy raw material in the air,
After preparing a cast ingot and coarsely pulverizing the ingot, a classification process is performed to prepare a coarse powder having the same maximum particle size, and the coarse powder is wet-attrited with an organic acid salt containing nitrogen in the form of an amine. After being flattened by a ball mill and maintained at a predetermined temperature of 350 to 450 ° C. in a nitrogen atmosphere, it is maintained at a predetermined temperature of 150 to 250 ° C. in the air and cooled to perform nitriding and oxidation. And can be manufactured.

As the organic acid salt containing nitrogen in the form of amine, propylene diamine stearate, dicyclohexylamine caprylate, monoethanolamine benzoate, monoethanolamine phthalate, hexylmethyldiamine caprylate, xylenediamine propylate and the like are used. Although possible, propylene diamine stearate is most preferred.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An alloy raw material was melted in a high frequency in the air to produce a cast ingot, and the ingot was roughly pulverized, and then subjected to a classification treatment to adjust the maximum particle size to 50 μm. The coarse powder is flattened together with 5% by weight of propylene diamine stearate with respect to the coarse powder in a wet attritor ball mill, and kept at a predetermined temperature of 350 to 450 ° C. in a nitrogen atmosphere for 5 hours. 150-2
It is maintained at a predetermined temperature within 50 ° C. for 3 hours, then subjected to a nitriding treatment and an oxidizing treatment by cooling, and then classified to obtain a component composition shown in Tables 1 and 2, D ₁₀ ,
Flat Fe-based alloy powders of the present invention having D ₅₀ , d and D ₅₀ / d for flame-retardant magnetic shields (hereinafter referred to as powders of the present invention) 1 to 18 and flat F for comparative flame-retardant magnetic shields
e-base alloy powder (hereinafter referred to as comparative powder) 1 was produced.

Further, the powder flattened by a wet attritor ball mill without addition of an organic acid salt containing nitrogen in the form of amine is kept at a predetermined temperature of 350 to 450 ° C. for 5 hours in a nitrogen atmosphere. Then, the powder was gradually cooled to room temperature to prepare a comparative powder 2 and a conventional flat Fe-based alloy powder 1 for magnetic shielding (hereinafter, referred to as conventional powder).

[0020]

[Table 1]

[0021]

[Table 2] (* Indicates a value outside the range of the present invention)

These powders 1 to 18 of the present invention and comparative powders 1 to 1
_Hc and σ _s of Sample No. 2 and Conventional Powder 1 were measured, and the measured values are shown in Tables 3 and 4.

Further, a flame of a simple igniter is applied to the powders 1 to 18 of the present invention, the comparative powders 1 and 2, and the conventional powder 1;
The time until ignition was measured, and the results are shown in Tables 3 and 4. In this case, the flame of a simple igniter is applied to the powder, and the time required to ignite is less than 10 seconds, which corresponds to the dangerous goods Class 1 Class 1 or Class 2 flammable solid specified by the Fire Service Law,
If it is determined that there is no danger of combustion if the time until ignition exceeds 10 seconds, the time until ignition is 10 seconds
The measurement was performed to determine whether the time exceeded 2 seconds, and the flame retardancy was evaluated.

[0024]

[Table 3]

[0025]

[Table 4]

From the results shown in Tables 1 to 4, O: 3 to
Inventive powder 1 containing 6 at% and N: 0.05 to 2 at%
Nos. 18 to 18 show that the magnetic properties are less deteriorated compared to the conventional powder 1 and that the time required for ignition by igniting with the flame of a simple igniter is long, indicating that they are excellent in flame retardancy. Further, the comparative powder 1 containing more than 2 atomic% of N is not preferable as a magnetic shielding powder because H _c becomes too large and the σ _s decreases, and the comparative powder 1 containing less than 3 atomic% of O Is not preferable because it becomes flammable.

[0027]

According to the present invention, it is possible to provide a flat Fe-based alloy powder for a magnetic shield which is more excellent in flame retardancy than conventional ones, and brings about an industrially superior effect.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01F 1/00 H01F 1/00 C (72) Inventor Yasuaki Yoshioka 1-1-1 Ichigaya-Kaga-cho, Shinjuku-ku, Tokyo Dainihon Printing Co., Ltd. (72) Inventor Atsushi Umezawa 1-1-1 Ichigaya-Kagacho, Shinjuku-ku, Tokyo Dainichi Printing Co., Ltd. (72) Inventor Koichi Ishiyama 1-297 Kitabukurocho, Omiya-shi, Saitama Mitsubishi Materials Corporation In-house (72) Inventor Kazunori Igarashi 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Inside Mitsubishi Materials Research Laboratory (72) Inventor Koichiro Morimoto 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Mitsubishi Materials Research Institute

Claims (1)

[Claims] An average thickness d: 0.05 to 0.6 μm, and the particle size when the total weight becomes 10% from the smaller particle size obtained by a particle size distribution meter is D ₁₀ , 50. when the particle diameter at which became% and D _50, D _10: 4.5~10
A magnetic shielding powder having a diameter of ₅₀ μm, a D _{50 of} 10 to 40 μm, and an aspect ratio (D ₅₀ / d) of 20 to 200, wherein M is one of Al or Si or If there are two types,
Atomic%, M: 15 to 30%, Cr: 3 to 15%, O: 3 to 6%, N: 0.05 to 2%, the balance being Fe and unavoidable impurities. Flat Fe-based alloy powder for flame-retardant magnetic shielding.